I am using JDateChooser for a java swing project I am developing and in this, the date could be set in two ways: by the end user or programmatically.
So I have defined a propertychangelistener in the respective class(the variable trig is initialised to zero and maintains track on how many times a property change is listened).
public class WriteEntry{
private int trig=0;
private Date currentDate = new Date();
public JDateChooser dateChooser = new JDateChooser();
public CustomDate selectedDate = DateConverter.convertDate(currentDate);
private static String filename = StorageSpace.currentpath+CurrentUser.getInstance().getUserName()+"\\"+
Integer.toString(selectedDate.getYear())+"\\"
+Integer.toString(selectedDate.getMonth())+"\\"+Integer.toString(selectedDate.getDay())+".txt";
private JLabel dayinfo = new JLabel("");
private JTextArea contentfield = new JTextArea("");
private PropertyChangeListener lis = new PropertyChangeListener(){
@Override
public void propertyChange(PropertyChangeEvent e) {
System.out.println("triggered "+trig++);
if(dateBoundary()) {
selectedDate = DateConverter.convertDate(dateChooser);
filename = StorageSpace.currentpath+CurrentUser.getInstance().getUserName()+"\\"+
Integer.toString(selectedDate.getYear())+"\\"
+Integer.toString(selectedDate.getMonth())+"\\"+Integer.toString(selectedDate.getDay())+".txt";
}
else {
updateDateChooser(selectedDate);
}
if(isAlreadyWritten())
{
try {
updateEditFields(selectedDate, "content");
} catch (IOException e1) {
e1.printStackTrace();
}
}
else
{
contentfield.setText("Start writing here");
dayinfo.setText("You are making entry for: "+ new SimpleDateFormat("dd/MM/yyyy").format(dateChooser.getDate()));
}
}
};
WriteEntry() //constructor
{
dateChooser.setDateFormatString("dd MM yyyy");
dateChooser.addPropertyChangeListener(lis);
updateEditFields(DateConverter.convertDate(currentDate), "Start");
}
}
And here is the code for dateBoundary():
public static boolean dateBoundary() {
Object[] option = {"I get it","My Bad!"};
if(dateChooser.getDate().compareTo(currentDate)>0) {
JOptionPane.showOptionDialog(HomePage.getFrame(),"message1",
"",JOptionPane.DEFAULT_OPTION,JOptionPane.ERROR_MESSAGE,null,option,option[0]);
return false;
}
if(dateChooser.getDate().compareTo(DateConverter.convertfromCustom(CurrentUser.getInstance().getDob()))<0){
JOptionPane.showOptionDialog(HomePage.getFrame(),"message2",
"",JOptionPane.DEFAULT_OPTION,JOptionPane.ERROR_MESSAGE,null,option,option[0]);
return false;
}
return true;
}
Code for isAlreadyWritten():
public static boolean isAlreadyWritten() {
File f = new File(filename);
if(f.length()!=0)
{
Object[] option = {"Read","Edit"};
JOptionPane.showOptionDialog(HomePage.getFrame(),"You already updated diary for this day. Do you want to edit?",
"",JOptionPane.DEFAULT_OPTION,JOptionPane.INFORMATION_MESSAGE,null,option,option[0]);
return true;
}
else
return false;
}
Code for updateDateChooser():
public static void updateDateChooser(CustomDate date) {
dateChooser.removePropertyChangeListener(lis); //to stop it from getting triggered when date is set programatically
dateChooser.setDate(DateConverter.convertfromCustom(date));
dateChooser.addPropertyChangeListener(lis);
}
Code for updateEditFields():
public static void updateEditFields(CustomDate searchDate, String excontent) {
updateDateChooser(searchDate);
selectedDate = DateConverter.convertDate(dateChooser);
dayinfo.setText("You are editing entry for: "+ new SimpleDateFormat("dd/MM/yyyy").format(dateChooser.getDate()));
contentfield.setText(excontent);
}
Now my dateboundary function is working as expected. whenever a date greater than current date is chosen, the optiondialog gets displayed and its gone after a click, and the datechooser is set to the last selected date, although the propertychange method is called thrice:
But my isAlreadyWritten() is not working as expected and the optiondialog is getting displayed 4 times with propertychange() method being called four times: once before each time the dialog is displayed.
I want to understand why propertychange is being called 4 times even though the datechooser is detached from the listener when the date is set programatically?
So, I put together this quick snippet and ran it
import com.toedter.calendar.JDateChooser;
import java.awt.EventQueue;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Date;
import javax.swing.JFrame;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JDateChooser dateChooser = new JDateChooser();
dateChooser.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
System.out.println(evt.getPropertyName());
}
});
dateChooser.setDate(new Date());
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(dateChooser);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
I opened the date selector and selected a date. The program outputted...
date
ancestor
date
date
ancestor is it getting added to the containerSo, as you can see, not only are you getting spammed with a lot of "date" property changes, you're also getting all the "other" property changes as well 😓
So, the first thing you want to do, is limit the the notifications to the "date" property only, something like...
dateChooser.addPropertyChangeListener("date", new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
System.out.println(evt.getPropertyName());
}
});
This at least means you don't get bother by all the additional information you don't care about.
While you can add and remove the listener, I tend to find it a pain, as I don't always have a reference to the listener(s), instead, I tend to use a state flag instead
private boolean manualDate = false;
//...
dateChooser.addPropertyChangeListener("date", new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (manualDate) {
return;
}
System.out.println(evt.getPropertyName());
}
});
manualDate = true;
dateChooser.setDate(new Date());
manualDate = false;
Not a big change, but this alone means that you're now down to two event notifications.
Instead, you should compare the oldValue with the newValue of the PropertyChangeEvent
JDateChooser dateChooser = new JDateChooser();
dateChooser.addPropertyChangeListener("date", new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (manualDate) {
return;
}
Date newDate = (Date) evt.getNewValue();
Date oldDate = (Date) evt.getOldValue();
if (newDate != null && oldDate != null) {
LocalDate newLD = LocalDate.ofInstant(newDate.toInstant(), ZoneId.systemDefault());
LocalDate oldLD = LocalDate.ofInstant(oldDate.toInstant(), ZoneId.systemDefault());
if (newLD.equals(oldLD)) {
return;
}
}
System.out.println(evt.getPropertyName());
}
});
And now, we're down to one change event. The only draw back is it won't tell you when they reselect the current date.
A slightly better work flow might be to ignore it all and simply have a JButton that the user can press to perform what ever associated actions you need carried out
import com.toedter.calendar.JDateChooser;
import java.awt.EventQueue;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.time.LocalDate;
import java.time.ZoneId;
import java.util.Date;
import javax.swing.JFrame;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
private boolean manualDate;
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JDateChooser dateChooser = new JDateChooser();
dateChooser.addPropertyChangeListener("date", new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (manualDate) {
return;
}
Date newDate = (Date) evt.getNewValue();
Date oldDate = (Date) evt.getOldValue();
if (newDate != null && oldDate != null) {
LocalDate newLD = LocalDate.ofInstant(newDate.toInstant(), ZoneId.systemDefault());
LocalDate oldLD = LocalDate.ofInstant(oldDate.toInstant(), ZoneId.systemDefault());
if (newLD.equals(oldLD)) {
return;
}
}
System.out.println(evt.getPropertyName());
}
});
manualDate = true;
dateChooser.setDate(new Date());
manualDate = false;
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(dateChooser);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}